Traction increasing device



Sept. 26, 1939.

J. W. LOGAN, JR

TRACTION INCREASING DEVICE Filed April 17, 1957 3 Sheets-Sheet 1 ATTORNEY Sept. 26, 1939. J. wjLoGAN, JR

TRACTION INCREASING DEVICE s' Sheets-Sheet 2 Filed April 17, 1937 INVIENTQR JOHN W. L OG AN,JF(.

ATTORNEY P 1939- J. w. LOGAN JIR 2,173,944

TRACTION INCREASING DEVICE Filed April 17, 1937 3 Sheets-Sheet 3 P I a f 1 Ir I} 1 j I v I u -I| fl 5 I}? [1) WHWM g Q W i MN MW Q w I lm .AH'I "II!" l hm -l u j O O OI) g in Pg w- M :2 Q 5 {1" r I 5 a l RE Q I l WW, W Hm i 1mm I M NH i F) W" O i r'h c0 1 Q1 60 I n". ,r umm" u; w I 1 1 WWII 1! I l INVEN I R JOHN w. LOGAN,JE

3% ATTORNEY Patented Sept. 26, 1939 UNITED STATES PATENT OFFICE TRACTION INCREASING DEVICE Application April 1'7, 1937, Serial No. 137,449

17 Claims.

. This invention relates to a brake equipment for a railway vehicle and more particularly to improved means to increase the adhesion between the vehicle wheels and the rails on which they 5 operate.

It has heretofore been proposed to employ an electromagnet or booster carried by a vehicle truck to exert force during an application of the brakes to supplement the force exerted by the 16 weight of the vehicle to press the vehicle wheels against the rails. The magnets heretofore employed have not engaged the rail, but have been spaced therefrom a short distance, at all times, with the result that these magnets have not been able to exert very large forces tending to press the vehicle wheels against the rails.

In addition, it has heretofore been proposed to provide a magnetic track brake shoe which is adapted to be moved adjacent to or into engage- 20 m-ent with the rail, and to be energized to hold the shoe in engagement with the rail to create retarding force between the track brake shoe and the rail. At relatively high vehicle speeds the braking force created by a magnetic track brake shoe is relatively small, and is substantially less than would result if the force employed to hold the track brake shoe against the rail were employed to increase the force pressing the vehicle Wheels against the rails, thereby increasing the 0 adhesion between the wheels and the rails and permitting greater braking forces to be applied through the vehicle wheels.

As a magnetic track brake shoe is held in engagement with the rail during an application, a substantially greater magnetic pull is developed between the shoe and the rail for a similar expenditure of excitation power than is developed by the magnetic adhesion boosters heretofore prolvided, in which the magnets are spaced from the rail at all times.

It is an object of this invention to provide an improved brake equipment for a railway vehicle, the brake equipment including means to create retarding force on the vehicle wheels, and. means described and incorporating means automatically operable on a predetermined application of the brakes to first efiect movement of the track shoe into engagement with the rail, and to effect enermoved away from the. rail toeffect a reduction in H the braking effect permitted through the vehicle wheels to thereby prevent wheel sliding.

A further object of the invention is to provide an improved vehicle brake equipment of the type described and incorporating means responsive to the rate of retardation of the vehicle for controlling the degree of braking effect transmitted through the vehicle Wheels, together with means controlled by the adhesion increasing means for controlling the operation of the retardation responsive means.

Another object of the invention is to provide an improved vehicle brake equipment of the type described and incorporating a deadman control device, and having means operative on: the re lease of manually applied pressure from the deadman control device to automatically condition the retardation controller to permitthe maximum rate of retardation.

A further object of the invention is to provide an improved vehicle brake equipment of the type described and incorporating means automatically operable on the release of manually applied pressure from the deadman control device to effect operation of the adhesion increasing means to increase the adhesion between the vehicle wheels and the rails, and to condition the brake applying means to produce the maximum degree of braking effect on the vehicle wheels.

Another object of the invention is to provide an improved vehicle brake equipment of the type described and incorporating means to delay the release of the adhesion increasing means to insure that the means for exerting braking force through the vehicle wheels will be released enough to prevent wheel sliding when the adhesion in-v creasing means is released. 7

A further object of the invention is to provide, an improved vehicle brake equipment. 7

Other objects of the invention and features of novelty will be apparent from the following description taken in connection with the accompanying drawings, in which,

Figs. 1 and 1A taken together form a diagrammatic view of a vehicle brake equipment embodying this invention,

Fig. 2 is a fragmentary sectional view taken substantially along the line 22 of Fig. 1, and

Fig. 3 is an elevational view of the truck of a vehicle equipped with the apparatus provided by this invention.

Referring to the drawings the vehicle brake equipment shown therein incorporates fluid pressure braking means including a brake cylinder I for exerting braking eifect through suitable brake rigging and brake shoes upon the vehicle wheels to retard the vehicle. While fluid pressure operated braking means is shown, it should be understood that the invention is not limited to this form of braking means to exert braking effort through the vehicle wheels, and that the use of other types of the braking means, such as hy- \draulic, dynamic, or other forms, is contemplated.

The brake equipment shown in the drawings includes a supply reservoir 2, an application magnet valve device 4, and a release magnet valve device 5. The supply of current to the windings, not shown, of these magnet valve devices is controlled by a retardation control device which is indicated generally by the reference numeral 1, and which has associated therewith a deadman control device or foot pedal device indicated generally by the reference numeral 8 by which the rates of retardation which the retardation control device is adjusted to effect may be adjustably varied.

The application magnet valve device 4 comprises a body having a chamber m therein which is constantly connected with the supply reservoir 2. The application magnet valve device 4 also has a chamber I2 therein which is constantly connected by Way of a passage and pipe M- with the brake cylinder I. A valve 15 ismounted in the chamber l2 and controls communication between the chamber I0 and the chamber [2. The valve I5 is yieldingly urged to the open position by a spring l6, while the, valve is moved to the seated position on energization of the winding, not shown, of the magnet valve device.-

The release magnet valve device 5 comprises a body having a chamber. l8 therein which is constantly connected with the brake cylinder l by way of the passage and pipe l4. A valve 20 is mounted in the chamber l8 and-is yieldingly urged to the seated position by a spring 2| to cut off communication between the chamber I8 and the atmospheric passage 22. On energization of the winding, not shown, of'the release magnet valve device 5 the valve 20 is movedagainst the Spring 2| away from its seat to open communication from the chamber IE to the atmosphere through the passage 22.

The retardation control device 1 is embodied in a casing having formedthereon a trackway indicated at and adapted to receive wheels 26 which support a movable weighted body 28. The body 28 is yieldingly urged toward the left, as viewed in Fig. 1 of the drawings, by a spring 30 mounted on a rod 32 which has one end thereof secured to the body 28, while the other end of this rod extends through andis guided by a bore in the casing of the retardation control device. The retardationcontrol device I is mounted on the train or vehicle so that when the train or vehicle is decelerating the weighted body 28 is urged to the right against the opposition ofthe spring 30 according to the rate of retardation of the vehicle or train.

Rigidly secured to the under side of the body 28 is a downwardly extending fin 34, while a similar upwardly extending fin is secured to the upper side of the body 28, as is best shown in Fig. 2 of the drawings.

The fin 34 is adapted to control the operation of the service photo-electric means, preferably of the type sometimes referred to briefly as photo-electric cell devices, and designated in its entirety by the reference numeral 38. The fin 35 is similarly adapted to control the operation of a like emergency photo-electric means, designated in its entirety by the reference numeral 39, and to also control the operation of photo-electric means designated by the reference numeral 40.

As is clearly shown in Fig. 2 of the drawings, the photo-electric means 38 comprises two lamps 42 and 43, which are adapted to be connected to a suitable source of current, not shown, by means of wires indicated at 44 in Fig. 2, but not shown in Fig. l of the drawings. The lamps 42 and 43 are adapted to produce light beams which when uninterrupted impinge upon photo-electric cell devices 45 and 46, respectively, the light beams being depicted by dotted lines in the drawings. The characteristic of the photo-electric cell devices 45 and 4B of importance is that each of these devices will produce an electric current when a beam of light is impinged thereon, but when the beam of light is interrupted, as by the passage of the fin 34 between the light source and the photo-electric cell, the electric current will immediately diminish substantially to zero or to a low ineffective value.

The photo-electric means 39 is substantially a duplicate of the photo-electric means 38, the photo-electric cells thereof being designated in Fig. 1 of the drawings by the numerals 48 and 49.

The photo-electric means is likewise substantially a duplicate of the photo-electric means 38, and consists of light producing lamps 59 and 5|, and photo-electric cells 52 and 53.

The photo-electric means 39 and are supported on brackets which are carried by a rod 55 which is adjustably supported from the casing of the retardation control device 1. The rod 55 is held in the adjusted position by means of a collar 56 and a set screw 51.

The photo-electric means 38 is mounted on a slide or crosshead member 58 having tongues extending from the ends thereof, which are slidable in grooves or slots formed in the casing of the retardation control device. One end of a link 60 is pivotally connected to the crosshead 58, while the other end of this link is pivotally connected to one arm of a bell crank 62 which is pivotally supported on the casing of the retardation control device. The other arm of the bell crank 62 has one end of a link 63 pivotally connected thereto, while the other end of this link is pivotally connected to the end of an arm 64 formed integral with a foot pedal 65 of the foot pedal device 8. The arm 64 is pivotally sup ported by means of a pin 66 on the end of an arm or lever 68, which is pivotally supported by means of a pin 89 on a portion of the vehicle structure indicated at 10. A coil spring H is mounted on the rod 63 and extends between a collar on the end of this rod and the vehicle structure 70, and yieldingly urges the right hand end of the arm 64 upwardly, as viewed in Fig. 1 of the drawings, to the position in which the crosshead 58 is held adjacent the left hand end of the casing of the retardation control device 1, which is the release position of the crosshead 58. 'A coil spring 12 extends between the portion 10 of the vehicle structure and the lever 58 and yieldingly urges this lever in a clockwise direction about the pin 69 upon the release of manually applied pressure from the heel portion of the foot pedal 65, so that an insulating block 14 carried by an arm of the lever 98 engages a movable contact 16 and moves the contact carried thereby away from a stationary contact 18.

One terminal of the winding of the application magnet valve device 4 and of the winding of the release magnet valve device 5 are connected by way of a wire 89 to one terminal of a suitable source of current, such as the battery indicated. at 8|. The other terminal of the winding of the release magnet valve device 5 is connected by way of a wire 83 to a stationary contact associated with a relay 85 which has a movable contact 85a associated therewith to which is connected a Wire 81 which leads to the other terminal of the battery 8|.

One terminal of the winding of the relay 85 is constantly connected by way of a wire 99 to one terminal of each of the photo-electric cells 45 and 46 of the photo-electric means 39. The other terminal of the winding of the relay 95 is connected by way of a wire 99 to a movable contact 9|a associated with a relay 9|. Upon energization of the winding of the relay 9| the movable contact 9|a engages a stationary contact which is connected by way of a wire 99 to a movable contact 9511 associated with a relay 95. When the winding of the relay 95 is deenergized, the

movable contact 95a engages a stationary contact which is connected by way of a wire 95 to the other terminal of the photo-electric cell. 45.

One terminal of the winding of the relay 9| is connected by way of a branch of the wire 89 to one'terminal of thebattery 9|, while the other terminal of the winding of the relay 9| ,is connected by way of a wire 91 to the stationary contact 18 associated with the foot pedal device '8. On the application of manually applied pressure to the heel portion of the pedal 95 insulating "element 14 carried by the lever 99 is moved out of engagement with the movable contact 16 and permits this contact to be moved into engagev ment with the stationary contact 19. The movable contact 16 is constantly connected by way of a branch of the wire 81 with one terminal of the battery 8!, with the result that when the movable contact 19 engages the stationary contact 18, a circuit is established through the winding of the relay 9! and causes the movable contacts thereof to be moved to their upper positions as shown in Fig. 1 of the drawings.

When the movable contact 9|a of the relay 9| is in its upper position as shown, therefore, a circuit is established from one terminal of the winding of the relay 85 to a terminal of the photo-electric cell 45, which circuit is traced through the wire 99 to the movable contact 9L1, of the relay 9|, wire 93 to the movable contact 95a; of the relay 95, and wire 96.

One terminal of the winding of the application magnet valve device 4 is connected by way of the wire 98 to a stationary contact associated with the relay 99. On energization of the winding of the relay 99 the movable contact 99a is held in engagement with this stationary contact, while the movable contact 99a has connected thereto a branch of the wire 81 leading from the battery 8|.

One terminal of the winding of the relay 99 is connected by way of a branch of the wire 89 to the photo-electric cell 46, while the other terminal of the winding of the relay 99 is connected by way of the wire N10 to a movable contact 9|b associated with the relay 9|. The movable contact 9|?) is adapted, while the winding of the relay 9| is energized, to engage a stationary contact which is connected by way of a wire with a movable contact 95b associated with the relay 95, which when the winding of this relay is deenergized, engages a stationary -''contact which is connected by way of a wire H13 to the other terminal of the photo-electric cell 46. It will be seen, therefore, that when the winding of the relay 9| is energized, which is the case at all times during normal operation of the vehicle as manually applied pressure is maintained on the heel portion of the pedal 65 of the foot pedal device 8, a circuit is maintained from the photo-electric cell 49 through the winding of the relay 99.

Operation during normal service applications and releases of the brakes The portion of the brake equipment thus far described is similar both in construction and operation to that shown in my U. S. Patent 2,017,667, issued October 15, 1935. During opera tion of this equipment, assuming that manually applied pressure is maintained on the heel portion of the pedal 65 of the foot pedal device 8 so that the movable contact 16 engages the stationary contact 18, thereby supplying current to the winding of the relay 9 and assuming also that the photo-electric means 38 is in the release position so that the light beams impinge upon the photo-electric cells of this means, the windings of the relays 95 and 99 will be energized with current supplied by the photo-electric cells 45 and 46, respectively.

As the winding of the relay 95 is energized, the movable contact 85a is maintained in the closed position, thereby establishing a circuit through the winding of the release magnet valve device with the result that the valve 29 thereof is held against the spring 2| to open communication between the chamber i8 and the atmosphere through the passage 22,'thus connecting the brake cylinder 1 to the atmosphere and releasing the brakes.

In addition, at this time, as the winding of the relay 99 is energized, the movable contact 99a is maintained in'the closed position tomaintain a circuit through the winding of the application magnet valve device 4 with the result that the valve I5 is held in the seated position to cut off the supply of fluid under presure from the supply reservoir 2 to the chamber I2 and thence to the brake cylinder When it is-desired to effect a normal service application of the brakes, pressure is maintained on the heel portion of the foot pedal, while the toe portion of the foot pedal 65 is depressed, causing the foot pedal 65 and the arm 54 to pivot about the pin 66. This movement of the arm 64- is transmitted through the link 63 and the bell crank 62 to the link 69, moving this link to the right, as Viewed in Fig. 1 of the drawings, and causing the crosshead or slide 58 to move to the right a distance in accordance with the downward movement of the foot pedal65.

On initial movement of the crosshead or slide 58, the fin 34 intercepts the light beam from the lamp 42 to the photo-electric cell 45, thereby interrupting the supply of current to the wind- 'ing of the relay 85. Upon interruption of the supply of current to this winding, the movable contact 85a thereof moves to the open position, thus interrupting the circuit to the winding of the release magnet valve device 5. On the interruption of the supply of current to the winding of this magnet valve device, the valve eleinent I8 is moved to the seated position by the spring 2|, thus cutting oif communication between the brake cylinder I and the atmosphere.

Upon further movement of the crosshead or slide 58, the supply of light to the photo-electric cell 46 is cut off, thereby cutting off the supply of current to the winding of the relay 99. On the interruption of the supply of current to the winding of this relay the movable contact 99a is moved to the open position, thus interrupting the supply of current to the winding of the application magnet valve device 4, and upon the interruption of the supply of current to this Winding the valve I5 is moved to the open position by the spring I6 to permit fluid under pressure supplied from the supply reservoir 2 to the chamber I to flow to the chamber I2, and thence by way of the passage and pipe I4 to the brake cylinder I.

As a result of the supply of fluid under pressure to the brake cylinder I force is exerted by the brake cylinder piston to press the brake shoes against the vehicle wheels, not shown, to exert braking force through the wheels to retard the vehicle, and the resulting force of inertia acting ''on the weighted body 28 causes it to move to the right, as viewed by Fig. 1 of the drawings, against the spring 30. On this movement of the weighted body 28, the fin 34 carried thereby is moved relative to the photo-electric means 38.

If the rate of retardation exceeds a predetermined valve, dependent upon the position to which the photo-electric means 38 has been moved by operation of the foot pedal device 8, the fin 34 will be moved to a position in which the notched left-hand edge of the fin continues to intercept the beam of light from the lamp 42 to the photo-electric cell 45, but in which it does not intercept the beam of light from the lamp 43 to the photo-electric cell 46. On movement of the fin 34 to this position current is again supplied by the photo-electric cell 46 to the wind.- ing of the relay 99, and upon energization of this winding the movable contact 99:: is moved to the closed position to establish the circuit from the battery 8I through the winding of the application valve device 4. On the supply of current to this winding the valve I is moved to the seated position to cut off the supply of fluid under pressure to the brake cylinder I, thereby preventing a further increase in the degree of application of the brakes.

If the photo-electric means 38 remains in the position to which it has been moved, and if there is a further increase in the rate of deceleration of the vehicle, the weighted body 28 will be moved farther to the right against the spring 30, and the fin 34 will be moved to a position in which it no longer intercepts the beam of light from the lamp 42 to the photo-electric cell 45. When the fin 34 is moved to this position the photoelectric cell 45 again supplies current to the winding of the relay 85, and upon energization of this winding the movable contact 85a is moved to the iromits seat against the spring 2I to open communication from the chamber I8 to the atmosphere through the passage 22, thereby releasing fluid under pressure from the brake cylinder and effecting a decrease in the degree of application of the brakes.

As a result of this reduction in the degree of application of the brakes, there will be a decrease in the rate of retardation of the vehicle, and a corresponding decrease in the force of inertia operating on the weighted body 28, with the result that the spring 30 will move the body 28 to the left from the position to which it has been moved by the force of inertia. If the photoelectric means 38 remains in the position to which it has been moved, the fin 34 may be moved to a position in which it again intercepts the supply of light from the lamp 42 to the photoelectric cell 45, and if this condition occurs, current will no longer be supplied by the photoelectric cell 45 to the Winding of the relay 85 and the movable contact 85a thereof will be moved to the open position to interrupt the 'circuit to the winding of the release magnet valve device 5 with the result that this magnet valve device will be operated to again out ofi the release of fluid from the brake cylinder, thus preventlng a further decrease in the degree of application of the brakes. I

On the release of manually applied pressure from the toe portion of the foot pedal 65 while pressure is maintained on the heel portion thereof, the spring II returns the photo-electric means 38 to the position in Which it is shown in Fig. 1 of the drawings, in which position the fin 34 does not intercept the light beams associated with the photo-electric cells 45 and 46. These cells then supply current to the relays associated therewith, and these relays condition the magnet valve devices to cut off the supply of fluid under pressure to the brake cylinder and to release fluid therefrom, thus effecting the release of the brakes.

Construction of means for limiting degree of application of the brakes on normal service application The photo-electric means 39 associated with the retardation control device "I operates tolimit the rate of retardation which this device permits,- and to thereby limit the degree of application of the brakes to a value which will not produce wheel sliding.

It will be seen that one terminal of each of" the photo-electric cells 48 and 49' is connected to a branch of the wire 89, which is connected to the windings of the relay 85 and 99, and that the other terminal of the photo-electric cell 48 has connected thereto a wire I05 which is connected to a stationary contact which is adapted to be engaged by a movable contact I08c'of a relay I08 when this contact is in its lower position.

It will be seen also that the other terminal of the photo-electric cell 49 is connected by way of a wire I86 with a stationary contact adapted to be engaged by a movable contact I081) associated with the relay I08. The relay I08 has another movable contact I08a associated therewith andadapted to engage a stationary contact which is connected by way of a wire III] with a contact Ill which is supported by suitable insulating material from the body of the retardation control device I. The movable contact I08a is connected by way of a wire II2 with one terminal of the winding of the relay 85, the other terminal of which is connected by way of the wire 80 to one terminal of the battery 8|.

The movable contact II 1 associated with the retardation control device 1 is adapted at certain times to engage a stationary contact H4 which is connected by a branch of the wire 81 to one terminal of the battery 8|. n

The winding of the relay I98 is deenergized except at certain times, as will hereinafter more fully appear, with the result that during service applications of the brakes the movable contacts 18a, 1980, and [080 associated with the relay I08 remain in the positions in which they are shown in Fig. 1 of the drawings.

The movable slide or crosshead 58 is provided with a shoe indicated at H5 which is arranged to engage the end of the movable contact Ill when the slide or crosshead 58 has been moved to a position to hold the cells 45 and 46 of the photo-electric means 38 substantially in the same vertical plane as the cells 48 and 49 of the photoelectric means 39. When the shoe H5 engages the end of the movable contact I I I, it presses the movable contact downwardly so that the contact touches the stationary contact H4, thereby establishing a circuit leading from the battery Si by way of the wire 8'! through the contacts H4 and III to the wire III! to the movable contact l98a, which is in the closed position at this time, as explained above, and thence to the wire H2 leading to one terminal of the winding of the relay 95. The other terminal of the winding of the relay 95 is connected to the other terminal of the battery 8| by way of the wire 80 so that a circuit is established through the winding 01' this relay.

Upon energization of the winding of the relay 95 the movable contacts 950. and 95b thereof are moved from the positions in which they are shown in Fig. l of the drawings, to positions in which the contact 95a engages a stationary contact which is connected by way of the wire I98 to one terminal of the photo-electric cell 49 associated with the photo-electric means 39. By this movement of the contact 95a the circuit leading from the photo-electric cell 45, associated with the photo-electric means 38, through the wire 99 to the winding of the relay 85 is interrupted, while the winding of the relay 85 is connected to the photo-electric cell 49, as explained above.

On this movement of the movable contact 951) the circuit leading from the photo-electric cell 46, associated with the photo-electric means 38, through the wire I83 and thence to the winding of the relay 99 is interrupted, while the movable contact 95b is moved into engagement with a stationary contact which is connected by way of the wire N35 with the photo-electric cell 48, associated with the photo-electric means 39.

It will be seen, therefore, that when the movable slide or crosshead 58 has been moved by the foot pedal device 8 to a predetermined position in its range of movement, the shoe H5 engages the movable contact HI and causes it to engage the contact H4 to thereby energize the winding of the relay 95, thus causing the control of the relays 85 and 99 to be transferred from the photo-electric cells 45 and 46, respectively, to the photo-electric cells 49 and 48, respectively.

Operation of means for limiting degree of application of the brakes On the initialmovement of the slide or crosshead 58 to the right from the position in which it is shown'in Fig. 1 of'the drawings, it is-moved to a position in which the fin 34 intercepts the light beams from the lamps 42 and 43 with the result that the photo-electric cells 45 and 45 no longer supply current to the windings of the relays 85 and 99, causing these relays to cut off the supply of current to the windings of the release magnet valve device 5 and of the application magnet valve device 4 to effect an application of the brakes, as explained in detail above. As a result of the interruption of the light beams directed at the photo-electric cells 45 and 45, therefore, there will be an application of the brakes in effect when the slide 58 is moved to the position in which the shoe H5 engages the end of the movable contact I l l to cause it to complete the circuit through the winding of the relay 95 and cause the control of the relays 85 and to be shifted from the photo-electric cells 45 and 45 to the photo-electric cells 49 and 48.

On the movement of the slide or crosshead 58 to the position to effect the transfer of the control of the relays 85 and 99 to the photo-electric cells 49 and 48, the weighted body 28 will be in a position in which the fin 35 carried thereby intercepts the beams of light directed at the photo-electric cells 49 and 48, with the result that when the control of the relays 85 and 99 is transferred to these photo-electric cells, the windings of these relays remain deenergized and the movable contacts thereof remain in their open positions and continue to interrupt the supply of current to the windings of the release magnet valve device 5 and the application valve device 4.

As a result of the'supply of fluid under pressure to the brake cylinder l, the vehicle will decelerate and the force of inertia operating upon the weighted body 28 causes this body to move against the spring 39. On this movement of the body 28 the fin 35 is moved, and when the rate of retardation of the vehicle reaches a predetermined value, the fin 35 will be moved to a position in which the notched end thereof continues to intercept'the light beam directed at the photo-electric cell 49, but no longer intercepts the light beam directed at the photo-electric cell 48. As a result of the supply of light to the photo-electric cell 48, a current is generated by this cell which is supplied by way of the wire 105 andthrough-the movable contact 9511 of the relay 95 .to the wire HH, and thence by way of the contact 9lb and the wire I99 to one terminal of the relay 99. The other terminal of this relay is connected by way of the wire 89 to the other terminal of the photo-electric cell 48. On the supply of current to the winding of the relay 99 the movable contact 99a thereof is moved to the closed position to complete the circuit through the winding of the application magnet valve device 4, and the valve l5 thereof is thereupon moved to the seated position to cut off the supply of fluid under pressure from the'supply reservoir 2 to the brake cylinder l, and thus prevent a further increase in the degree of application of the brakes.

If the rateaof retardation of the vehicle continues to increase, there will be further movement of the Weighted body 28 against the spring 39, and the fin 35 carried bythe body 28 will be moved to a position in which the notched end thereof no longer intercepts the light beam directed at the photo-electric cell- 49, and this cell will generate an electric current which is supplied by way-of the wire I96 to the movable contact 95a of the relay 95, which contact is in its upper position at this time, as explained above. Upon the supply of current to the movable contact 95a current flows therefrom by way of the wire 93 to the movable contact 9Ia and through the wire 95 to one terminal of the winding of the relay 85, the other terminal of which is connected by way of the wire 89 to the other terminal of the photo-electric cell 49.

On the supply of current to the winding of the relay 85 the movable contact 85a is moved to the closed position to complete the circuit through the winding of the release magnet valve device 5, whereupon the valve 20 is moved away from its seat to release fluid under pressure from the brake cylinder I, and thus decrease the degree of application of the brakes and prevent possible wheel sliding.

The photo-electric means 39 is positioned so that the weighted body 28 will be moved to a position in which the fin 35 carried thereby no a longer intercepts the light beams directed at the photo-electric cells 48 and 49 when the rate of retardation of the vehicle is slightly less than the rate which is effective to result in wheel sliding. As a result, therefore, the increase in the degree of application of the brake means will be prevented, while fluid will be released from the brake cylinder to limit the degree of application of the brakes to a degree less than that which is effective to cause wheel sliding.

It will be seen, therefore, that when the pedal 65 of the application means 8 is depressed more than a predetermined amount and causes the slide or crosshead 58 to be moved beyond a predetermined point in its range of movement, the

control of the braking means is automatically transferred from the photo-electric means 38 carried by the slide 58, to the photo-electric means 39 which operates to limit the degree of brake application efi'ected.

Similarly, on the release of pressure from the toe portion of the pedal 65 the spring II expands and effects movement of the crosshead or slide 58 to the left, as view in Fig. 1 of the drawings, while the shoe H5 is moved away from the movable contact III and permits this contact to disengage the stationary contact II4, thus interrupting the circuit to the winding of the relay 95. As a result this relay operates to transfer control of the brake equipment from the photo- 'electric means 39 back to the photo-electric means 38 carried by the slide or crosshead 58, and this photo-electric means operates, as described in detail above, to control the degree of application of the brakes in accordance with the position of the crosshead 58.

Construction of adhesion. increasing means The brake equipment provided by this invention incorporates means automatically operable on a relatively heavy application of the brakes to increase the force effective to press the vehicle wheels against the rails to thereby increase the force of adhesion between the wheels and the rails, while this means also operates to condition the retardation control device I to effect a higher rate of retardation than that normally permitted by this device.

The brake equipment provided by this invention includes track shoes I20 which are associated with a truck, not shown, of the vehicle and are netic force of attraction between the track shoes and the rails I22.

The vehicle also has associated therewith means adapted to control movement of the track shoes I20 into and out of engagement with the rails I22, and also operating at certain times, as will hereinafter more fully appear, to exert force between the vehicle and the track shoes tending to lift the track shoes away from the rails, thereby causing downwardly directed force to be exerted on the vehicle to press the vehicle wheels against the rails with substantial force supplementing the force exerted by the weight of the vehicle.

As is clearly shown in Fig. 1a and Fig. 3 of the drawings, each of the track shoes I20 has pivotally connected thereto at each end one end of a link I24, the other end of each of which is connected to one end of an arm I25. Each of these arms has its other end secured to a bracket I26 carried by a portion of the vehicle structure, such as one of the vehicle trucks.

While only one lifting means is shown in connection with each track shoe in Fig. 1a. of the drawings it should be understood that each shoe is provided with lifting means at each end, or that suitable linkage is provided to enable one such lifting means to simultaneously lift both ends of the shoe.

Each of the brackets I26 has associated therewith lifting means indicated generally by the reference numeral I21 and comprising a body I28 having a bore therein in which is mounted a piston I30 provided with a stem which is pivotally connected to one of the arms I25 at a point intermediate the point of connection of the arm I25 with the bracket I26 and with the link I24.

The pistons I30 have at the lower faces thereof chambers I32 adapted to be supplied with fluid under pressure, and as will be understood, on an increase in the pressure of the fluid in the chambers I32 force is exerted through the pistons I30 upon the arms I25, and this force is transmitted through the links I24 to exert upwardly directed force upon the track shoes I20 tending to move them away from the rails I22, while a similar force is exerted through the bodies I28 and the brackets I26 upon the vehicle structure to press the vehicle wheels against the rails.

This brake equipment includes a valve device indicated generally by the reference numeral I35 and provided with a chamber I36 which is connected by way of a branched pipe I38 with the chambers I32 in the bodies I28. Each branch of the pipe I38 is provided with a choke or restricted portion I39 for restricting the rate of supply of fluid under pressure to or the release of fluid under pressure from the chamber I32.

The valve device I35 also has a chamber I 40 therein which is constantly connected by way of a pipe I4I with a source of fluid under pressure, such as the supply reservoir 2.

A double seating valve element I42 is mounted in the chamber I36 to control communication from the chamber I40 to the chamber I36, and to also control communication between the chamber I38 and an atmospheric passage I44. The valve element I42 is provided with the seat adapted to engage a seat rib surrounding a passage leading from the chamber I40, and is provided with another seat which is adapted to engage a seat rib surrounding a passage leading from the chamber I36 to the atmospheric passage I 44. A spring I46 is mounted in the chamber I 40 and yieldingly urges the double seating valve element I42 to its upper seated position, in which a seat carried thereby engages the seat rib surrounding the passage leading fromthe chamber I36 to the atmospheric passage I44, and in which communication is opened from the chamber I40 to the chamber I36.

The stem of the valve element I42 has secured thereon a piston I41 which is mounted in a bore in the body of a valve device I35, and has at its upper face a chamber I48, which is constantly connected by way of a pipe I49 with a chamber I52 of a magnet valve device I50. The chamber I52 is constantly connected to the atmosphere by way of a restricted port I54, while the body of the valve device I50 has a chamber I55 therein which is constantly connected by way of a pipe I56 with a volume reservoir I58 which is proportioned to hold a predetermined quantity of fluid under pressure. The valve device I50 has, in addition, a chamber I59 therein, which is constantly connected by way of a pipe I60 to the pipe I4I leading from the supply reservoir 2.

A double seating valve element I62 is mounted in the chamber I55 to control communication between the chamber I55 and the chamber I52, and to also control communication between the chamber I59 and the chamber I55. A spring I63 is mounted in the chamber I59 and yieldingly urges the double seating valve element I52 to its upper seated position to cut off communication from the chamber 55 to the chamber I52, and to permit communication between the chamber I50 and the chamber I55 so that fluid under pressure is supplied from the reservoir 2 to the chamber I55 and thence by way of the pipe I56 to the reservoir I58 to charge this reservoir with fluid under pressure. Upon energization of the winding, not shown, of the magnet valve device I50 the double seating valve element I62 is moved to its lower seated position to cut off the supply of fluid under pressure to the chamber I55 and to permit fluid to flow therefrom to the chamber I 52, and thence by way of the pipe I49 to the chamber I48 at the face of the piston I41 of the valve device I35.

One terminal of the winding of the magnet valve device I50 is connected to one side of the battery 8| by way of a branch of the wire 00, while the other terminal of the winding of the magnet valve device I50 is connected by way of a wire I64 to the wire I I0, and thus to the movable contact III associated with the retardation control device 1.

The brake equipment also includes means associated with the retardation control device I for controlling the energization of the track shoes I20. The brake equipment includes a retarded release relay I65 having a movable contact I66 which controls a circuit between the trolley I68, and a wire I69 which is connected to one terminal of the windings of each of the track shoes I20, while the other terminals of these windings are connected to ground. The movable contact I66 is normally biased to the open position, and upon energization of the winding of this relay, the contact IE6 is moved to the closed position, while upon the interruption of the supply of current to the winding of the relay I65 the movable contact I66 is held in the closed position for a brief time interval to maintain the circuit through the windings of the track shoes for a purpose to be hereinafter more fully explained.

One terminal of the winding of the retarded relay I65 is connected to one terminal of the battery 8| by way of a. branch of the wire 80, while the otheer terminal of the winding of the relay I65 is connected by way of a branch of the wire I64 to the movable contact III so that when the slide or crosshead 58 of the retardation control device 1 is moved to the position in which the shoe II presses against and closes the movable contact I I I, current is supplied to the winding of the retarded relay I65, and results in the supply of current to the windings of the track shoes.

The lifting means I21 associated with the track shoes I20 have associated therewith means for controlling the energization of the winding of the relay I08 to thereby determine whether the degree of application of the brakes on the vehicle is limited by the photo-electric means 39, or by the photo-electric means 40.

One terminal of the winding of the relay I08 is connected to one terminal of the battery 8! by way of a branch of the wire 80, while the other terminal of the winding of the relay I08 is connected by way of a wire I to a stationary contact which is adapted to be engaged by a movable contact I12 associated with the lifting means I21 for one of the track shoes I20. The movable contact I 12 is yieldingly urged to the closed position by means of a spring I14, while the lower end of the stem of the contact is adapted to be engaged by the arm I25 on a predetermined upward movement of this arm to move the contact against the spring I14 to the open position. The movable contact I12 is adapted to engage another stationary contact which is connected by way of a wire I16 to a stationary contact which is adapted to be engaged by a. movable contact I18. The movable contact I 18 has a spring I30 associated therewith and yieldingly urging the contact to the open position, while this contact has a movable abutment in the form of a diaphragm I82 associated therewith and operated upon a predetermined increase in the pressure of the fluid in the chamber I32 of the lifting means I21 to move the movable contact I 18 against the spring I80 to the closed position.

The movable contact I18 is also adapted to engage a stationary contact which is connected by way of a wire I83 with a stationary contact associated with the movable contact !18 associated with the lifting means I21 for the other of the track shoes I20. This movable contact is also adapted to engage a stationary contact which is connected by way of a wire I16 with a stationary contact which is adapted to be engaged by a movable contact I12, while this movable contact I12 also engages a stationary contact which is connected by way of a wire I85 with a terminal of the battery 8I. It will be seen, therefore, that the movable contacts I12 and the movable contacts I18 are arranged in series and control the circuit from one terminal of the battery 8! to one terminal of the winding of the relay I 08, while the other terminal of this winding is constantly connected to the other terminal of the battery. When all of the movable contacts above referred to are in their closed positions a circuit is established through the winding of the relay I08, while this circuit is interruptedif any of the movable contacts are in their open positions.

When each of the track shoes is provided with separate lifting means for each end, the contacts I12 and I18 of the various lifting means are con"- nected in series in the manner described above so that the circuit controlled by these contacts will be interrupted in the event that any one of the contacts is in its open position.

operation of adhesion increasing means while brakes are released and during normal service applications of the brakes During operation of the vehicle with the brakes released, and with pressure applied to the heel portion of pedal 65 to maintain the insulating element 14 out of engagement with the movable contact 16, as shown in Fig. l of the drawings, and also during normal service applications of the brakes, the supply and release of fluid under pressure to and from the brake cylinder I is controlled by the photo-electric means 38, as described in detail above.

At these times the movable contact I I I does not engage the stationary contact 4, and hence current is not supplied from the wire 81 to the wire H0, and to the wire I64 leading to the retarded relay I65 and to the winding of the magnet valve device I50. Accordingly the windings of this relay and of the magnet valve device I50 are deenergized. As the winding of the retarded relay is deenergized, the movable contact I66 of this relay is maintained in the open position with the result that the windings of the track shoes I20 are deenergized.

In addition, as the winding of the magnet valve device I50 is deenergized, the double seating valve element 562 of this valve device is maintained in its upper seated position by the spring I63 to cut off the supply of fluid under pressure from the chamber I55 to the chamber 552, and to permit the supply of fluid under pressure from the supply reservoir 2 to the chamber I55 and thence by way of the pipe I56 to the reservoir I58 to charge this reservoir with fluid at the pressure supplied from the reservoir 2.

At this time the chamber I52, being connected to the atmosphere by way of the restricted passage I54, is at atmospheric pressure and fluid at atmospheric pressure is present in the chamber I48 at the face of the piston I41 of the valve device l35. Accordingly, the double seating valve element I42 of the valve device I35 is held in its upper seated position by the spring I46 to cut off communication from the chamber I36 to the atmospheric passage I44, while communication is opened between the chamber I40 and the chamber I36 so that fluid under pressure supplied from the supply reservoir 2 to the chamber I40 flows to the chamber I36, and thence by way of the branched pipe I38 and through the restricted passages or chokes I39 to the chambers I32 at the lower faces of the pistons I of the lifting means I21 associated with the track shoes I20, The pressure of the fluid in these chambers, therefore, will be substantially the same as in the reservoir 2, and the force exerted by this fluid under pressure upon the pistons I30 is sufficient to hold the levers or arms I25 in the positions in which they are shown and cause the track shoes I20 to be held away from the rails I22, while the levers or arms I25 engage the lower ends of the stems of the contacts I12 and hold them against the springs I14 to interrupt the circuit controlled thereby. 7

At this time, because of the relatively high pressure present in the chambers I32, the diaphragms I82 associated with the movable contacts I18 maintain these contacts intheir closed positions against the springs I 80; However, at

movable contacts I08a, I083, and I080 are maintained in the positions in which they are shown in Fig. 1 of the drawings.

Operation of brake equipment on relatively heavy applications If, at this time, the operator desires to effect a relatively heavy application of the brakes and exerts force upon the toe portion of the pedal 65 of the foot pedal device 8 to move it downwardly substantially to the end of its range of movement, the crosshead or slide 58 will be moved to a position in which the shoe H5 carried thereby engages and presses upon the movable contact II I to cause it to engage the contact II4 to complete a circuit from the battery through the wire 81 to the wire IIO, to which is connected the wire I64. On the supply of current to the wire I I0, current flows through the movable contact l08a, associated with the relay I08, to the winding of the relay 05 and this relay is operated to cause the movable contacts 95a and 95b to transfer the control of the relays 85 and 99 from the photoelectric means 38 to the photo-electric means 39, as explained in detail above.

In addition, upon the supply of current to the wire I I 0, current flows to the wire I64 and to the winding of the retarded relay I65, and upon energization of this winding the movable contact I 66 is moved to the closed position to complete the circuit from the trolley I68 through the windings of the track shoes I20 to energize these windings.

In addition, upon the supply of current to the wire I64, current is supplied to the winding of the magnet valve device I50 and the double seating valve element I62 thereof is moved against the spring I63 to its lower seated position to cut off the supply of fluid under pressure to the chamber I55 and thence to the reservoir I58, while communication is opened from the reservoir I58 and the chamber I55 to the chamber I52, from which fluid under pressure flows by way of the pipe I49 to the chamber I48 at the face of the piston I41 of the valve device I35.

On an increase in the pressure of'the fluid in the chamber I48 force is exerted on the piston I41 to move the double seating valve element I42 downwardly against the spring I46 to thereby cut off the supply of fluid from the supply reservoir 2 and the chamber I40 to the chamber I36, from which fluid is supplied to the chambers I32 of the lifting means I21 associated with the track shoes. In addition, upon this movement of the double seating valve element I42 fluid is released from the chamber I36 to the atmosphere through the passage I44, and fluid is accordingly released from the chambers I32 at the faces of pistons I30 at restricted rates through the chokes I39.

On the release of fluid under pressure from the chambers I32, there is a decrease in the force exerted on the pistons I30 and these pistons are no longer able'to maintain the track shoes I 20 out of engagement with the rails I22, and the shoes are thereupon moved into engagement with the rails I22, while the arms I 25 aremoved downwardly and permit 'the'springs I14 to move the movable contacts I12 to their closed positions.

The windings of the track shoes I20 are ener-' g'ized at this time by current supplied from the trolley I68 by the relay I65, and a relatively great magnetic force of attraction is created tending to maintain the track shoes in engagement with the rails as soon as the shoes are moved into engagement with the rails.

In addition, on the release of fluid under pres- -sure from the chambers I 32 there is a corresponding reduction in the force exerted on the diaphragms I82 and the springs I associated with the movable contacts I18 move these contacts to their open positions, thus interrupting the circuit controlled thereby. The various parts of the equipment are arranged and proportioned so that the movable contacts I18 will be operated to interrupt the circuit controlled thereby before the movable contacts I72 are operated to engage the contacts associated therewith, with the result that the circuit through the winding of the relay I08 will be maintained deenergized during move ment of the track shoes I20 into engagement with the rails.

On movement of the double seating valve element I42 of the magnet valve device I55 to its lower seated position to permit the supply of fluid under pressure from the reservoir I58 to the chamber I 43 at the face of the piston I41 of the valve device I35, fluid under pressure is vented from the chamber I52 through the restricted passage I54 at a restricted rate.

After a relatively short time interval, the pressure or" the fluid remaining in the reservoir I58, and in the chamber I48 at the face of the piston Ml, will be reduced by the release of fluid through the restricted passage I54 so that the force exerted upon the piston I41 by this fluid under pressure is insufficient to maintain the piston 47 and the double seating valve element I42 against the opposing force of the spring I46. As a result, therefore, the double seating valve element I22 is moved from its lower seated position to its upper seated position by the spring I45 to cut oif communication between the chamber I36 and the atmospheric passage I44, and to open communication from the chamber I40 to the chamber I36 to permit fluid under pressure supplied from the supply reservoir 2 to flow to the branched pipe I38, and thence through the restricted passages or chokes I39 to the chambers i32 at the faces of the pistons I30.

At this time, as pointed out above, the windings of the track shoes I20 are energized by current supplied thereto from the trolley I58, and, accordingly, a relatively great magnetic force of attraction is created tending to maintain the track shoes I20 in engagement with the rails I22.

On the supply of fluid under pressure to the chambers I32 the pressure in these chambers builds up and force is exerted through the pistons I30 tending to lift the shoes away from the rails. The various parts of the equipment are arranged and proportioned, however, so that when the pressure of the fluid in the chambers I32 has equalized with the pressure of the fluid in the reservoir 2, a predetermined force is exerted by the pistons E30 upon the track shoes I20 tending to lift them away from the rails, and also so that this force is less by a predetermined amount than the magnetic force of attraction tending to hold the track shoes against the rails. Accordingly, the track shoes I20 will be maintained in engagement with the rails so that the maximum magnetic force of attraction will be developed between the track shoes and the rails as a result of the energization of the windings of these shoes.

As the track shoes I20 remain in engagement with the rails, some braking force is developed between these shoes and the rails and tending to retard the vehicle. However, because of operation of the lifting means associated with the track shoes, only limited force is available to press the shoes against the rails, and, according- 1y, only limited braking force is developed between the track shoes and the rails.

In addition to the force exerted by the lifting means tending to lift the shoes away from the rails, an equal, but opposite force is developed through thevehicle structure by this means on the vehicle wheels, not shown, tending to press the vehicle wheels against the rails. This force is in addition to, and supplements, the force exerted on the vehicle wheels by the weight of the vehicle which is supported on the wheels. As the vehicle wheels are pressed against the rails with a force exceeding that exerted by the weight of the vehicle alone, there is substantially greater adhesion between the vehicle Wheels and the rails on which they operate, and, accordingly, substantially greater braking effect can be transmitted through the vehicle wheels without producing wheel sliding than would be the case if this supplementary orradditional force was not present to press the vehicle wheels against the rails.

The vehicle equipment provided by this invention incorporates means automatically operable while the adhesion increasing means is conditioned to increase the adhesion between the vehicle wheels and the rails to condition the retardation control device I to control the brake equipment to produce a higher degree of braking effect through the vehicle Wheels than was previously permitted by this device.

As stated above, On the release of fluid under pressure from the chambers I32, the levers I25 are moved downwardly, while the track shoes I20 are moved into engagement with the rails. Upon this movement of the arms I25 the springs I14 associated with the movable contacts In move these contacts to their closed positions, and on the subsequent resupply of fluid under pressure to the chambers I32 the track shoes I20 are held in engagement with the rails and the levers I25 are not moved upwardly far enough to cause the contacts M2 to be moved to their open positions.

In addition, on an increase in the pressure of the fluid in the chambers I32 substantially to the value normally carried in these chambers, so that substantially the normal amount of force is exerted on the track shoes tending to lift them upwardly, the diaphragms 582 are moved against the springs I80 and move the movable contacts I18 to their closed positions, thus completing the circuit from the battery to the Winding of the relay I08.

On the supply of current to the winding of the relay I08 the movable contacts I08a, I08b and I080 are moved from the position in which they are shown in Fig. l. The movable contact I08a is moved away from the contact to which is connected the wire IIO, thereby interrupting the circuit from the battery 8| to the winding of the relay with the result that the movable contacts 95a and 95b of this relay are moved to the positions in which they are shown in Fig. 1.

As a result of this movement of the movable contacts 95a and 95b, the control of the brake equipment is transferred from the photo-electric means 39 back to the photo-electric means 38, as described in detail above, with the result that even though the weighted body 28 is moved by the force of inertia to a position in which the fin 35 carried thereby permits the light beams associated'with the photo-electric cells 48 and 69 to impinge upon these cells, current will not be supplied from these cells to the windings of 75 the relays 85 and 99. The windings of these relays will be maintained deenergized until the weighted body 28 is moved to a position in which the fin 34 carried thereby permits the light beams associated with the photo-electric cells 45 and 86 to impinge upon these cells. Because of the position to which the crosshead 58 has been moved the weighted body 28 will not be moved to this position until the body has been moved somewhat farther to the right against the spring 30 than is required to move the fin 35 out of the path of the light beams associated with the photo-electric means 39, and, accordingly, the retardation control device I will be conditioned to produce a somewhat higher degree of braking effect through the vehicle wheels than is produced by operation of the photo-electric means 39.

At this time, because the adhesion between the vehicle wheels and the rails is increased by operation of the adhesion increasing means, a higher degree of braking effort may be transmitted through the vehicle wheels without producing wheel sliding.

The various parts of the retardation control device I are arranged and proportioned so that the photo-electric means 38 cannot be moved to the right, as viewed in the drawings, beyond a point at which the retardation control device I is operative toproduce a predetermined maximum rate of retardation of the vehicle and a corresponding maximum degree of application of the brakes. This maximum degree of brake application which can be effected by the retardation control device I by this movement of the photo-electric means 38 is less than that which will produce wheel sliding while the adhesion between the vehicle wheels and the rails is augmented by operation of the adhesion increasing means.

Accordingly, the degree of application of the brakes will be controlled by the photo-electric means 38, and when the weighted body 28 is moved to the position to permit the light beams associated with the cells 45 and 46 to impinge upon these cells, currents will be suppplied to the relays 85 and 99 to condition these relays to supply current to the windings of the magnet valve devices 4 and 5, and thus control the degree of application of the brakes. As will be understood, the degree of application of the brakes which the photo-electric means 38 is effective to produce varies in accordance with the position to which this means is moved by operation of the pedal 65.

Operation of equipment in event of failure of the adhesion increasing means If the track shoes I20 should lose their grip on the rails I22 for any reason, such as failure of the supply of current by the trolley I68 to the windings of the track shoes, the increased adhesion between the vehicle wheels and the rails produced by the adhesion increasing means provided by this invention and operating through the track shoes will be lost. If the same high degree of braking effect is maintained through the vehicle wheels after this reduction in the adhesion between the vehicle wheels and the rails, wheel sliding may result.

The brake equipment provided by this invention, therefore, incorporates means operable automatically in the event that the track shoes lose their grip on the rails to condition the retardation control device I to permit only that degree of application of the brakes which can be transmitted through the vehicle wheels without producing wheel sliding while the adhesion between the wheels and the rails is not augmented by operation of the adhesion increasing means.

If the track shoes I20 should lose their grip on the rails I22 for any reason, there will be a reduction in the force opposing upward movement of the track shoes and the fluid under pressure present in thechambers I32 of the lifting means I2! will expand and move the pistons I30 upwardly very rapidly, thereby lifting the track shoes I29 away from the rails. On this upward movement of the pistons I38 there is a corresponding rapid increase in the volume in the chambers I32, while there will be a similar rapid reduction in the pressure of the fluid in these chambers as fluid under pressure is supplied to these chambers only at restricted rates through the chokes I39.

On this sudden reduction in the pressure of the fluid in the chambers I32 there is a corresponding reduction in the pressure of the fluid operating on the diaphragms I82, and the springs I88 move the movable contacts I18 from their closed positions to their open positions, thus opening the circuit through the winding of the relay I98.

On deenergization of the winding of the relay I08 the movable contacts I88a, i981), and H380 thereof are moved from their upper positions to the positions in which they are shown in Fig. l of the drawings. On this movement of the contact I08a it engages the contact to which is connected the wire H8, which is energized at this time as the contact III is held in engagement with the contact I I4 by the shoe I I5, with the result that current is supplied to the winding of the relay 95, and the movable contacts 95a and 95?] thereof are moved from the positions in which they are shown in Fig. 1 of the drawings to their upper positions to thereby transfer control of the relays 85 and 99 from the photo-electric means 38 to the photo-electric means 39.

It is assumed that at this time pressure is maintained on the heel portion of the pedal 65 of the foot pedal device 8 so that the insulating member 14 is held out of engagement with the movable contact 16 and permits this contact to engage the stationary contact 78 to supply current to the wire 91, and thus to the winding of the relay 9I so that the movable contacts 9| a, 9Ib, and 9 I0 thereof are maintained in the positions in which they are shown in Fig. 1 of the drawings.

If at the time the control of the relays 85 and 99 is transferred from the photo-electric means 38 to the photo-electric means 39, the vehicle is decelerating at a relatively rapid rate, the weighted body 28 will be held by the force of inertia in a position in which the fin 35 carried thereby does not interrupt the light beams directed at the photo-electric cells 18 and 49. These cells, therefore, will generate electric currents which will be supplied to the windings of the relays 85 and 99, and these relays will thereupon operate to supply current to the windings of the magnet valve devices 4 and 5 to cause these valve devices to cut off the supply of fluid under pressure to the brake cylinder and to release fluid under pressure therefrom, and thus reduce the degree of brake application effected through the vehicle wheels.

As a result of this reduction in the degree of application of the brakes on the vehicle there will be a reduction in the rate of retardation of the vehicle and the weighted body 28 will be moved by the spring 35 to the left, as viewed in Fig. l of the drawings, and when the weighted body 28 has been moved to a predetermined position, the notched left hand end of the fin 35 will intercept the light beam directed at the photo-electric cell 49 and this cell will no longer generate current. Current, therefore, will not be supplied to the Winding of the relay 55 and this relay will operate to cut off the supply of current to the winding of the release magnet valve device with the result that the valve 20 thereof will be moved to the seated position by the spring H to cut off the release of fluid under pressure from the brake cylinder I.

If there is a further reduction in the rate of retardation of the vehicle, the weighted body 28 will be moved farther to the left by the spring 35, and the fin 35 will cut off the light beam directed at the photo-electric cell 48, thereby interrupting the supply of current to the winding of the relay 9%. This relay will then operate to cut oif the supply of current to the winding of the application magnet valve device 4 the valve I5 thereof will be moved to the open position by the spring I5 to permit the supply of fluid under pressure from the supply reservoir 2 to the brake cylinder I to increase the degree of application of the brakes and cause the rate of retardation of the vehicle to be maintained at the value determined by the photo-electric means 39,

It will be seen, therefore, that if for any reason the track shoes I25 lose their grip on the rails R2 the retardation control device I will be automatically conditioned to effect only that degree of application of the brakes permitted by the photo-electric means 39. As pointed out above, this photo-electric means is arranged to effect only that degree of application of the brakes which can be transmitted through the vehicle wheels without producing wheel sliding when the adhesion between the vehicle wheels and the rails is not augmented by operation of the adhesion increasing means.

Release after a relatively heavy application If after a relatively heavy application of the brakes has been efiected, and While the adhesion increasing means is functioning, manually applied pressure is released from the toe portion of the pedal 55 of the foot pedal device 8 to permit the toe portion to be moved upwardly by the spring II, the crosshead or slide 58 carrying the photo-electric means 38 is moved to the position in which it is shown in Fig. l of the drawings, and on this movement of the crosshead 53, the shoe H5 carried thereby is moved out of engagement with the movable contact I I I and this contact is separated from the stationary contact I M. On movement of the contact l i I away from the contact M4 the circuit from the battery 85 by way of the wire 81 to the wire H5 is interrupted, While no current will be supplied from the wire III? to the wire I64 leading to the retarded relay I55. On the interruption of the supply of current to the retarded relay I55, this relay continues to maintain the circuit controlled thereby for a predetermined time interval with the result that the windings of the track shoes 25 remain energized and a powerful magnetic force is maintained to hold these shoes in engagement with the rails.

On movement of the photo-electric means 33 towards the release position, if the vehicle is in motion and its movement is being retarded at a substantial rate, the weighted body 28 will be held by inertia against the spring 35 with the result that beforethe photo-electric means 38 is moved all the way to the release position the fin 34 is no longer operative to intercept the light beams directed at the photo-electric cells 45 and 45, and these cells will supply current to the windings of the relays 85 and 59 to operate these relays to supply current to the windings of the application and release magnet valve devices 4 and 5 to cut off the supply of fluid under pressure to the brake cylinder and to release fluid under pressure therefrom, thereby reducing the degree of application of the brakes.

As the retarded relay I65 is maintained in the closed position for a time interval after the interruption of the circuit through the winding of this relay, the circuit through the windings of the track shoes I20 is maintained and the track shoes are efiective to increase the adhesion between the vehicle wheels and the rails, and to exert a retarding force on the vehicle for a time interval subsequent to the movement of the photo-electric means 38 towards the brake releasing position, thus giving the brake controlling mechanism an opportunity to reduce the pressure of the fluid in the brake cylinder l thereby reduce the degree of application of the brakes before the adhesion increasing means is released.

In addition, upon the movement of the crosshead 58 to a position to permit the movable contact HI to disengage the stationary contact 5M and thereby interrupt the supply of current to the wire I54, the supply of current to the Wind-- ing of the magnet valve device I50 is interrupted, and the double seating valve element I52 of this magnet valve device is moved by the spring I53 from the lower seated position to the upper seated position to cut off communication between the chamber I55 and the chamber l52, and to permit communication between the chamber I59 and the chamber I55, thereby permitting fluid under pressure supplied from the supply reservoir 2 to flow to the reservoir I58 to charge this reservoir with fluid under pressure.

After a predetermined time interval, the movable contact I66 of the retarded relay I55 is moved to the open position, thereby interruptin the circuit to the windings of the track shoes 225, thus causing the magnetic force of attraction between the shoes and the rails to decrease. On this reduction in the force tending to hold the shoes in engagement with the rails, the fluid under pressure present in the chambers I32 of the lifti-ng means I2'I exerts sufiicient force through the pistons I30 to lift the track shoes E25 away from the rails- I22.

On this movement of the pistons I30 there is an increase in the volume of the chambers I32 and a corresponding reduction in the pressure of the fluid present therein, as fluid under pressure is supplied to these chambers only at a restricted rate through the chokes 639, with the result that an appreciable time interval will elapse before the pressure of the fluid in the chambers I32 is increasedto the pressure of the fluid in the reservoir 2 by the supply of fluid thereto through the chokes I39.

On the reduction in the pressure of the fluid in the chambers I32 resulting from movement of the pistons 30, there is a corresponding reduction in the pressure of the fluid acting upon the diaphragms I82 and the springs Hi5, therefore, move the movable contacts I18 away from the stationary contacts associatedtherewith, thus causing the circuit controlled by these contacts to be interrupted substantially as soon as the pistons I30 operate tomove the shoes I20 away from the rails I22.

Upon further movement of the pistons I30 the arms I25 engage the ends of the movable contacts I12 and move these contacts against the springs I14 so that they interrupt the circuit which is also controlled by the contacts I18.

After a further brief time interval, the pressure of. the fluid in the chambers I32 will have been increased by the supply of fluid through the chokes I39 substantially to the pressure of the fluid in the supply reservoir 2, and on this increase in the pressure of the fluid in the chambers I32, the force exerted through the diaphragms I82 is sufficient to move the movable contacts I18 against the springs I80 to their closed positions, but before this action occurs, the circuit controlled by the movable contacts I18 will have been interrupted by the movable contacts I12.

On operation of either of the movable contacts I18 or I12 to interrupt the circuit controlled thereby, the circuit through the winding of the relay I08 is interrupted. On the interruption of the circuit through the winding of the relay I08, the contact I080, is moved to its closed position in which it engages the stationary contact to which is connected to the wire IIO, but this is without effect as the wire IIO has already been deenergized by movement of the shoe II5 out of engagement with the contact III, thereby permitting the contact III to move away from the contact II4. Accordingly, the winding of the relay 95 remains deenergized, and the contacts 95a and 95b remain in the positions in which they are shown in Fig. 1 of the drawings.

In addition, upon deenergization of the winding of the relay I08, the contacts I08b and I080 are moved to the positions in which they are shown in Fig. 1 of the drawings, but their movement is without effect as the circuits through these contacts are interrupted by the movable contacts 9 la and 9Ib', which at this time are in their upper positions, as shown in Fig. 1 of. the drawings, assuming that pressure is maintained on the heel portion of the pedal 65 so that the contact 16 engages the contact 18 and supplies current to the winding of the relay 9|.

The control of the brake equipment, therefore, remains in the photo-electric means 38, while the track shoes I20 remain in their upper positions out of engagement with the rails until a further relatively high degree of brake application is desired by the operator.

Operation of the brake equipment on a deadman emergency application The brake equipment provided by this invention also operates automatically in the event of the release of manually applied pressure from the heel portion of the pedal 65 of the foot pedal device 8 to automatically effect operation of the adhesion increasing means, and to condition the braking means to produce the maximum permissible braking effect through the vehicle wheels.

On the release of manually applied pressure from the heel portion of the pedal 65, the spring 12 moves the lever 68 about the pin 69 so that the insulating element 14 engages the movable contact 16 and moves it away from the stationary contact 18, thereby interrupting the supply of current to the wire 91 from the wire 81, which is connected to the battery 81. When the supply of current to the wire 91 is cut off, the supply of current to the winding of the relay 9| is cut off, and the movable contact 9Ic associated with this relay is moved into engagement with a stationary contact to which is connected a branch of the wire 81 so that current is supplied from the Wire 81 to the wire I64, which is connected to the movable contact 9Ic.

On the supply of current to the wire I64 by the movable contact 9lc, current is supplied to the winding of the relay I65, and the movable contact I65 of this relay is moved to the position to establish the circuit from the trolley I68 to the windings of the track shoes I20.

In addition, upon the supply of current to the Wire I64, current is supplied to the winding of the magnet valve device I50, and this valve device is operated, as described above, to cut off the supply of. fluid under pressure to the reservoir I58, and to supply fluid from this reservoir to the valve device I35 to first condition this valve device to release fluid from the chambers I32 of the lifting means I21 associated with the track shoes I20, and to thereafter condition this valve device to supply fluid under pressure to the lifting means I21 associated with the track shoes.

As a result, therefore, the windings of the track shoes I20 will be energized and the track shoes will be moved into engagement with the rails I22, while fluid under pressure will thereafter be supplied to the lifting means to exert force between the track shoes and the vehicle structure to increase the force exerted on the vehicle wheels to press them against the rails, as described in detail above.

As a result of operation of the lifting means associated with the track shoes, the circuit from the battery through the Winding of the relay I 08 is completed, as described in detail above, and upon energization of the winding of this relay, the movable contacts associated therewith, are moved from the position in which they are shown in Fig. 1 of the drawings. As a result of movement of the movable contact I08a, the supply of current from the wire I64 to the winding of the relay 95 is cut off.

However, in the time interval subsequent to the supply of current by the contact Me of the relay 9| and prior to the interruption by the relay I08 of the circuit from the wire I64 to the winding of the relay 95, the winding of the relay 95 will have been energized and the movable contacts 95a and 95?) associated therewith, will have been moved from the positions in which they are shown in the drawings to their upper positions, thereby transferring control of the relays 85 and 99 from the photo-electric means 38 to the photoelectric means 39.

At this time the light beams associated with the cells of. the photo-electric means 39 are intercepted by the fin 35, and, accordingly, no current is supplied by these cells to the windings of the relays 85 and 99. The movable contacts of these relays, therefore, are moved to their open positions, if they are not already in their open positions, and no current will be supplied to the windings of the magnet valve devices 4 and 5. As a result, therefore, the valve 20 of the release magnet valve device 5 is moved to the seated position by the spring 2| to cut off the release of fluid under pressure from the brake cylinder I, while the valve I5 of the application magnet valve device 4 is moved to the open position by the spring I6 to permit the supply of fluid under pressure from the reservoir 2 to the brake cylinder I to efiect an application of the brakes.

As soon as current is supplied to the winding .of the relay M39 as a result of operation of the lifting means iil' associated with the track shoes 192, as explained in detail above, the movable contact [68a is moved to the open position and interrupts the circuit through the winding of. the relay 95 permitting the movable contacts 95a and 95b thereof to move to the positions in which they are shown in Fig. 1 of the drawings.

In addition, at the same time, the movable contact 8% moves from the position in which it establishes contact with a branch of the wire I06 to a position in which it engages a contact to which is connected a wire I89 leading from one 'terminal of the cell 53 of the photo-electric means so. The winding of the relay 9! isdeenergized at this time, because the contact 16 is held away from the contact '53, as explained above, and the movable contact Sic; engages a contact to which is connected 0. wire i542 leading from the contact ltdb, and a circuit is established from the photoelectric cell 53 through the winding of the relay 85 which is traced from the wire I89 through the movable contact M8?) to the wire l 82, and through the movable contact em to the wire 99 to one terminal of the winding 85.

f the winding 85 is connected by way of the wire 89 to the other terminal of the photo-electric cell 5'9.

Similarly, on upward movement of the movable contact I980 from the position in which it is shown in Fig. l of the drawings, it engages a contact to which is connected a wire 585 leading from one terminal of the photo-electric cell 52, while the movable contact 5980 is moved out of engagement with the contact to which is connected a branch of the Wire 5235. On this movement of the movable contact 5990, a circuit is established from the photo-electric cell 52 to one terminal of the winding of the relay 99 which is traced from the wire 585 through the movable contact 380 to a wire 83, which, at this time, is engaged by the movable contact 9 ib, which is connected by way of the wire 1% to one terminal of the Winding of the relay $39. ihe other terminal of the winding of the relay $9 is connected by way of the wire'89 to the other terminal of the photo-electric cell 52.

Accordingly, on movement of the arm or lever 98 of the foot pedal device 8 to the position to cause the movable contact 16 to be disengaged from the stationary contact '58 and thus interrupt the supply of current to the winding of the relay 9!, the control of the relays and 99 is first transferred from the photo-electric means 38 to the photo-electric means 39, and is thereafter transferred from the photo-electric means 39 to the photo-electric means 49 as soon as the adhesion increasing means has been operated to pro"- duce a predetermined degree of force to press the vehicle wheels against rails.

Operation in the event of failure of the adhesion increasing means during a, deadman emergency application If during an emergency application of the brakes produced by the release of manually applied pressure to the heel portion of the pedal 65 of the foot pedal device 8, the track shoes I20 lose their grip on the rails so that the increased adhe- ,sion between the vehicle wheels and the rails produced through the track shoes is lost, the brake equipment provided by this invention operates automatically to transfer control of the brakes are shown in Fig. 1 of the drawings.

The other terminal from the photo-electric means 49 to the photoelectric means 39 to thereby reduce the degree of application of the brakes to a value which will not produce wheel sliding.

If the track shoes I29 lose their grip on the rails M2 the contacts H8 or H2 associated with the lifting means 27 for the track shoes I20 will operate, as described in detail above, to interrupt the circuit from the battery 8i to the winding of the relay 598.

When the supply of current to the winding of the relay I99 is interrupted the movable contacts 5 58a, i882), and late, of this relay are moved from their upper position to the positions in which they By this movement the contacts 18b and H180 are moved out of engagement with the stationary contacts to which are connected the wires leading from the cells of the photo-electric means 40, and into engagement with stationary contacts to which are connected the wires leading from the cells of the photo-electric means 39 thereby transferring control of the braking means from the photo-electric means 553 to the photo-electric means 39, which thereupon operates, as described above, to reduce the degree of application of the brakes to a value which will not cause wheel sliding while the adhesion increasing means is ineffective.

On this movement of the contact IOBa, it engages the stationary contact to which is connected the wire i It, which at this time is supplied with current from the battery Bl by the wire I64 leading from the movable contact 9 lo of the relay 9 I. As a result, therefore, current will be supplied to the winding of the relay and the'movable contacts 950. and 95b thereof will be moved from the position in which they are shown in-Fig. 1 of the drawings to their upper positions in which they engage stationary contacts to which are connected wires leading from the photo-electric means 39. However, this movement of the movable contacts 95a and 95b is without effect as the circuits leading from these contacts are open at this time, since the movable contacts 9 la and 9 lb of the relay iii are in their lower positions.

Release after a deadman emergency Assuming that the control of the brakes has been retained by the photo-electric means 40, if it is desired to effect the release of the brakes following the application of the brakes by operation of the foot pedal device 9, pressure is applied to the heel portion of the pedal 65 and the lever 68 is pivoted about the pin 69 so that the insulating member M is moved away from the movable contact l5,'while this contact is moved into engagement with the stationary contact 18. Current is then supplied from the battery 3| by way of the wire 8! and the contacts l6 and 19 to the wire 91 andto the winding of the relay 9|. Upon energization of the winding of this relay the movable contacts 9 la, 9 lb and 9 lo thereof are moved from their lower positions to the positions in which they are shown in Fig. 1 of the drawings, in which the contact 9h: does not engage the stationary contact to which is connected the branch of the wire 8'! to thereby cut ofi the supply of current from the wire 8'! to the wire I64.

On the interruption of the supply of current to the wire I64 the winding of the magnet valve device I59 is deenergized and the double seating Valve element I62 thereof is moved by the spring I63 from its lower seated position to its upper seated position, and fluid under pressure is again supplied from the supply reservoir 2 to the reservoir I58 to charge this reservoir with fluid under pressure.

In addition, upon the interruption of the supply of current to the wire I64, the relay I65 is deenergized, and after a brief time interval, the movable contact I65 thereof is operated to open the circuit controlled thereby, and thus cut oh" the supply of current to the windings of the track shoes l2i3 which are thereafter lifted away from the rails, while the contacts H8 and I12 are operated, as explained in detail above, to interrupt the circuit to the winding of the relay 18.

In addition, upon the interruption of the supply of current to the winding of the relay SI, the movable contacts Ma and 9) move to their lower positions in which they engage the stationary contacts to which are connected the wires [82 and I85, respectively, thereby transferring control of the relays 85 and from the photo-electric means 40 back to the photo-electric means 38 carried by the crosshead 58 so that the degree of application of the brakes is thereafter controlled according to the position of the photoelectric means 38, as described in detail above.

While one embodiment of the improved vehicle brake equipment provided by this invention has been illustrated and described in detail, it should be understood that the invention is not limited to these details of construction, and that numerous changes and modifications may be made Without departing from the scope of the following claims.

Having now described my invention, what I claim as new and desire to secure by Letters Patent, is:

1. In a brake equipment for a vehicle adapted to run upon a rail, braking means for exerting braking force through the vehicle wheels, a manually operated member movable from a release position through an application zone for efifecting operation of the braking means, a magnetic track shoe adapted to engage the rail and being adapted when energized to be attracted thereto, lifting means associated with the vehicle and operated on the supply of fluid under pressure to exert force on the track shoe to move the shoe away from the rail and operated on the release of fluid under pressure to effect movement of the shoe into engagement with the rail, means controlled by said manually operated member for energizing said track shoe, and means controlled by said member for releasing fluid under pressure from said lifting means to effect movement of the track shoe into engagement with the rail and for thereafter supplying fluid under pressure to the lifting means to cause said lifting means to exert force on the track shoe tending to lift it away from the rail, whereby force is exerted tending to press the vehicle wheels against the rail.

2. In a brake equipment for a vehicle adapted to run upon a rail, braking means for exerting braking force through the vehicle wheels, a manually operable member movable to an application position to eflect an application of said braking means, electromagnetic means associated with the vehicle and operative when energized and when in its operating position to create a magnetic force of attraction for the rail, fluid pressure operated means interposed between said electromagnetic means and the vehicle wheels and operative on the release of fluid under pressure therefrom to effect movement of the electromagnetic means towards the rail to its operating position and being operative on the supply of fluid under pressure thereto while the electromagnetic means is energized and in its operating position to exert force on the electromagnetic means tending to lift said means away from the rail, whereby force is exerted on the vehicle wheels tending to press them against the rail, and means operative on movement of the manually operable member to its application position to first release fluid under pressure from said fluid pressure operated means and to thereafter supply fluid under pressure thereto.

3. In a brake equipment for a vehicle adapted. to run upon a rail, braking means for exerting braking force through the vehicle wheels, a

manually operable member movable to an ap plication position to eiiect an application of said braking means, electromagnetic means associated with the vehicle and operative when energized and when in its operating position to create a magnetic force of attraction for the rail, fluid pressure operated means interposed between said electromagnetic means and the vehicle wheels and operative on the relesae of fluid under pressure therefrom to effect movement of the electromagnetic means towards the rail to its operating position, and being operative on a supply of fluid under pressure thereto while the electromagnetic means is energized and in its operating position to exert force on the electromagnetic means tending to lift said means away from the rail, whereby force is exerted on the vehicle Wheels tending to press them against the rail, valve means normally establishing communication between a source of fluid under pressure and said fluid pressure operated means and operative on an increase in fluid pressure to cut off the supply of fluid to said fluid pressure operated means and to release fluid therefrom, means for releasing fluid from said valve means at a restricted rate, a timing reservoir adapted to be supplied with fluid under pressure, and means operative on movement on the manually operable member to its application position for cutting ofi the supply of fluid under pressure to the timing reservoir and for supplying fluid under pressure from said reservoir to said valve means.

4. In a brake equipment for a vehicle adapted to run upon a rail, braking means for exerting braking force through the vehicle wheels, a member responsive to inertia for controlling the degree of application permitted said braking means, electromagnetic means associated with the ve hicle, said means being movable between a normal position and an operating position and being operative in the operating position to create a force of attraction for the rail to thereby increase the adhesion between the vehicle wheels and the rails, and means controlled by said electromagnetic means for varying the degree of brake application permitted by said inertia responsive member.

5. In a brake equipment for a vehicle adapted to run upon a rail, braking means for exerting braking force through the vehicle wheels, a member responsive to inertia for controlling the degree of application permitted said braking means, electromagnetic means associated with the vehicle, said means being movable between a normal position and an operating position and being operative in the operating position to create a force of attraction for the rail to thereby increase the adhesion between the vehicle wheels and the rail, and means operative by movement of said electromagnetic means to its operating position to increase the degree of brake application permitted by said inertia responsive member.

6. In a brake equipment for a vehicle adapted to run upon a rail, braking means for exerting braking force through the vehicle wheels, a member responsive to inertia for controlling the degree of application permitted said braking means, electromagnetic means associated with the vehicle, said means being movable between a normal position and an operating position and being operative in the operating position to create a force of attraction for the rail to thereby increase the adhesion between the vehicle wheels and the rail, and means operative by movement of the electromagnetic means away from its operating position to decrease the degree of brake application permitted by said inertia responsive member.

7. In a brake equipment for a vehicle adapted to run upon a rail, braking means for exerting raking force through the vehicle wheels, a member responsive to'inertia for controlling the degree of application permitted said braking means, electromagnetic means associated with said vehicle, said means being movable between a normal position and an operating position and being operative in the operating position to create a force of attraction for the rail, actuating means interposed between said electromagnetic means and the vehicle wheels for exerting force tending to move the electromagnetic means from the operating position towards the normal position and thereby create a force tending to press the vehicle wheels against the rail, and means operated in accordance with the force exerted by said actuating means for varying the degree of brake application permitted by said inertia responsive member.

8. In a brake equipment for a vehicle adapted to run upon a rail, braking means for exerting braking force through the vehicle wheels, a member responsive to inertia for controlling the degree of application permitted said braking means, electromagnetic means associated with said vehicle, said means being movable between a normal position and an operating position and being operative in the operating position to create a force of attraction for the rail, fluid pressure operated actuating means interposed between said electromagnetic means and the vehicle wheels and operated on an increase in fluid pressure to exert force tending to move the electromagnetic means from the operating position towards the normal position and thereby create a force tending to press the vehicle wheels against the rail, and means responsive to the pressure of the fluid supplied to said fluid pressure responsive means for varying the degree of brake application permitted by the inertia responsive member.

9. In a brake equipment for a vehicle adapted to run upon a rail, braking means for exerting braking force through the vehicle wheels, a member responsive to inertia for controlling the degree of application permitted said braking means, electromagnetic means associated with said vehicle, said means being movable between a normal position and an operating position and being operative in the operating position to create a force of attraction for the rail, fluid pressure operated actuating means interposed between said electromagnetic means and the vehicle wheels and operated on an increase in fluid pressure to exert force tending to move the electromagnetic means irom the operating position towards the normal position and thereby create a force tending to press the vehicle Wheels against the rail, and means subject to and operated. on a predetermined reduction in the pressure of the fluid supplied to said pressure responsive means for reducing the degree of brake application permitted by said inertia responsive member.

10. In a brake equipment for a vehicle adapted to run upon a rail, braking means for exerting braking force through the vehicle wheels; a member responsive to inertia for controlling the degree of application permitted said braking means, electromagnetic means associated with said vehicle, said means being movable between a normal position and an operating position and being operative in the operating position to create a force of attraction for the rail, actuating means interposed between said electromagnetic means and the vehicle wheels for exerting force tending to move the electromagnetic means from the operating position towards the normal position and thereby create a force tending to press the vehicle wheels against the rail, and means controlled in accordance with the force exerted by said actuating means and also controlled by movement of the electromagnetic means away from the operating position for varying the degree of brake application permitted by said inertia responsive member.

11. In a brake equipment for a vehicle adapted to run upon a rail, braking means for exerting braking force through the vehicle wheels, a member responsive to inertia for controlling the degree of application permitted said braking means, electromagnetic means associated with said vehicle, said means being movable between a normal position and an operating position and being operative in the operating position to create a force of attraction for the rail, actuating means interposed between said electromagnetic means and the vehicle wheels and incorporating means operative on an increase in the pressure of the fluid in a chamber to exert force tending to move I the electromagnetic means from the operating position towards the normal position, means for supplying fluid under pressure to said chamber at a restricted rate, and means responsive to the pressure of the fluid in said chamber for varying the degree of brake applications permitted by said inertia responsive member.

12. In a brake equipment for a vehicle adapted to run upon a rail, braking means for exerting braking force through the vehicle wheels, a manually operable member movable from a release position through an application zone for effecting applications of said braking means in accordance with the range of movement of said member in said application zone, control means for limiting toa predetermined value the degree of brake application of said braking means efiected by said member, an electromagnetic element adapted to create a force of attraction for the rail, actuating means operating through said element for exerting force to press the vehicle wheels against the rail, and means responsive to the force exerted by said actuating means for rendering said control means efiective or ineffective.

13. In a brake equipment for a vehicle adapted to run upon a rail, braking means for exerting braking force through the vehicle wheels, application means'for effecting an application of said braking means, control means for limiting to one predetermined value the degree of brake application produced by said application means, other control means for limiting to a higher predetermined value the degree of brake application produced. by said application means, an electromagnetic element adapted to create a force of attraction for the rail, actuating means operating through said element for exerting force to press the vehicle wheels against the rail, and means responsive to the force exerted by said actuating means and determining which of said control means is effective to limit the degree of brake application.

14. In a brake equipment for a vehicle adapted to run upon a rail, braking means for exerting braking force through the vehicle wheels, application means for effecting an application of said braking means, control means for limiting to one predetermined value the degree of brake application produced by said application means, other control means for limiting to a higher predetermined value the degree of brake application produced by said application means, an electromagnetic element movable between a normal position and an operating position and being operative in the operating position to create a force of attraction for the rail, actuating means operating through said element for exerting force to press the vehicle wheels against the rail, and means responsive to the force exerted by said actuating means and also responsive to movement of said element away from its operating position for determining which of said control means is effective to limit the degree of brake application.

15. In a brake equipment for a vehicle adapted to run upon a rail, braking means for eifecting braking force through the vehicle wheels, an application member movable from a release position to an application position for efiecting an application of said braking means, an electromagnetic element operative when energized to create a force of attraction for the rail, actuating means operative through said element when said element is energized and exerting force to press the vehicle wheels against the rail, and means operative on movement of the application member to the application position for supplying current to said element, said means being also operative on movement of the application member from the application position towards the release position to maintain the supply of current to said element for a time interval and to thereafter cut off the supply of current to said element.

16. In a brake equipment for a vehicle adapted to'run upon a rail, braking means for exerting braking force through the vehicle wheels, a magnetic track shoe adapted to engage said rail, said track shoe having a winding which when ener-- gized causes the shoe to be attracted to the rail, supporting means associated with the track shoe and normally holding the track shoe above the rail and spaced therefrom, said supporting means being also operable when the track shoe is energized and in engagement with the rail to exert force between the shoe and the Vehicle tending to lift the shoe away from the rail whereby force is exerted on the vehicle tending to press the vehicle wheels against the rail, a manually operable member movable between a release position and an application position for efiecting applications of said braking means, and means controlled by said member and operable upon movement of said member to its application position to effect energization of the winding of said track shoe and to condition the supporting means to permit movement of the track shoe into engagement with the rail, said means being operable thereafter to maintain the winding of said shoe energized and to condition the supporting means to exert substantially greater force between the track shoe and the vehicle tending to lift the shoe away from the rail than was exerted by said supporting means during movement of the track shoe into engagement with the rail.

17. In a brake equipment for a vehicle adapted to run upon a rail, braking means for exerting braking force through the vehicle wheels, a manually operable member movable from a release position through an application zone for efiecting applications of said braking means, control means for limiting to a predetermined value the degree of brake application of said braking means effected by said member, an electromagnetic element adapted to create a force of attraction for the rail, actuating means operating through said element for exerting force to press the vehicle wheels against the rail, and means responsive to movement of said electromagnetic element away from its operating position for rendering said control means inefiective.

JOHN W. LOGAN, JR. 

